This description relates to inducing air.
In an internal combustion engine, for example, induced air from the ambient is mixed with fuel prior to combustion. Good combustion can be achieved if the induced air is homogeneous and the fuel-air mixture has a particular ratio.
As shown in FIG. 1, air is induced into an engine 10 of a typical automobile along an induction pathway that includes a breathing port 12, an air filtration system 14 within a housing the expansion room 15, intake port 16, tubing 18 leading to a throttle body 20 (shown schematically), to the atomization point, 21, where fuel injectors spray fuel into the induced air which is atomized within the induced air. Tubing 22 feeds the atomized fuel-air mixture from the atomization point into the combustion chambers 24 of the cylinders 26, where it is ignited by spark plugs 28 controlled by a timing mechanism 30.
The efficiency of the engine depends on the amount of oxygen that is available from the induced air to mix with the fuel at the point of atomization. The ambient air, and thus the induced air, contains about 21% oxygen and 78% nitrogen. A typical engine is designed to use an air/fuel ratio of about 1 to 14 by weight at the point of atomization.
As shown also in FIG. 2, the ambient air is inducted by the suction of the engine vacuum acting through the air filter 14 (which removes particles from the air) and into air expansion chamber 15, and through intake port 16, and through the piping 18 and an intake manifold 17 that lies along the length of the engine next to the intake ports 19 of the cylinders. The sucking occurs in cycles as each cylinder in turn undergoes an intake stroke as the piston is drawn away from its associated intake port 19. The cycling causes the air to be induced and to arrive at the intake manifold in successive bursts 30. The separation between successive bursts is smaller the higher the revolutions per minute (RPM) of the engine as selected by the driver using the throttle pedal. The timing between successive intake strokes also depends on the RPM. During the intake stroke of a given cylinder, one of the bursts of air is located at the right position along the intake manifold to be drawn into the atomization point 21 for mixture with the fuel.